***Disclaimer: I do not own these characters or anything else. This story is simply a fans interpretation.***
Also, please be kind fellow whovians, when it comes to cannon. I've only been a member of the fandom for a couple years, and might not have everything exactly right.
Secluded and alone, that was her life now. Even on the rare occasion that she did go into town, there was no one that she could relate to. She felt out of place with the forty year olds, that were closer to her appearance. She felt out of place with the elderly, that were closer to her age. She felt out of place in general, and yet she persisted. Why? Why bother? If it weren't for the unshakable feeling that she had some part yet to play, she would have no reason to go on. Bad Wolf had extended her life for some purpose, she just knew it. It had to be true, didn't it? Otherwise, there would be no answer to the question of 'why?'. When you are in love with Time's Champion, nothing happens by chance; every question is answered in time... Or was it with time?
Rain was falling softly on the grassy hill where the Tardis was parked. Permanently parked, she might add. She was sitting on the floor of the console room, with her legs hanging out the open door. The rain was turning her socks a darker shade of purple. She was watching the slow transition, when all at once, the time rotor behind her illuminated and began to churn.
Her head whipped around to face the sudden, yet not entirely unexpected, change. The Tardis herself had warned her that it would be happening soon. She got up to inspect the pulsing time rotor, running her hands along the smooth console affectionately. Alas, she could not pilot the ship alone, well, at least not without its complete cooperation. The stubborn police box had refused to budge for years.
As much as the Tardis was her home, it never truly belonged to her; not in the way it had belonged to him. The ship would always be bound to him, indefinitely. The fact that it continued to shelter her and care for her was an indication of the mutual love they shared: otherwise it too would have no reason to go on. Sad that it was only just now becoming full operational.
Sure, they had used it for trips around the world and even around the immediate star cluster in later years, but never through time. They didn't get the chance. Without ideal growing conditions or a way to acquire exotic alien parts to help it along, the Tardis formation process had taken much longer than expected. It had taken nearly two hundred years to clone a fully functional ship from a single coral strut.
There had been too many variables back then, back when they had started. The strictly linear progression of time was not something they had taken into account. Why would they have? How could they have known? Known that for some reason she was going to age slower than the half-human version of him... Known that Bad Wolf had tampered with her physiology to keep her alive for longer than should have been humanly possible. That's not to say that they didn't have many happy years together; one hundred and eighty happy years together to be exact, before old age had claimed him. It was only now that she understood why he had been so hesitant to love her, immortal as he was. Outliving the ones you care most about leaves you feeling empty and hollow. It was surreal, in that she had never considered the possibility that she would outlive him.
For eighteen years, Rose and the Tardis had mourned him together. And for eighteen years, the Tardis had refused to move, refused to fly without her usual pilot. The only difference was that now the ship could travel through time as well as space, if only she were willing to do so.
The rain was picking up outside, bowing the visible foliage under the weight of the water. Their little cottage looked saturated too, she would go check on it tomorrow to be sure that nothing had leaked. She rarely went down the hill to the old cottage any more. They had only lived in that 'same size on the inside' building (as he called it), until their Tardis was developed enough to house them comfortably. However, their rural piece of property still proved to be a good place to park their fledgeling time ship, since it was unable to enter the vortex.
Rose pulled the door closed for the night and picked up her supper dishes that were left on the jump seat. She thought about working more on her painting or reading more of her book before going to bed, but if she was honest with herself, sleeping was her favorite part of the day now... Well, usually...
In the years since... Since him... She had developed bright lucid dreams. Most of the time, they were detailed dreams about her adventures with the Doctor. Sometimes, they were nightmares filled with fire and screaming. Every once in a while, they were romantic in nature and she got the chance to make love to her dear Doctor again.
In what had become her nightly ritual, to encourage the romantic dreams, she flipped through their old photo album in the bed they used to share. It was always bitter sweet, but it reminded her that with a Time Lord anything was possible. She wouldn't put it past him to show up, out of the blue, somehow... Somehow, he would always come back for her. Perhaps that was her unknown purpose: to wait for him. Rose closed her eyes and descended into welcome slumber.
...
The Tardis explored her new grasp of time, flexed her wings so to speak. Not that she would ever use them. She would never leave her Thief, no matter how much she loved her Wolf. Time felt familiar to the ship, like déjà vu or a waking dream. The other version of herself had used time freely and frequently, and this version of her taped easily into the memory.
As the Tardis peaked into the time vortex, she was startled by another all but forgotten sensation. An incoming transmission? From whom?
Doctor? Could that really be you? We just picked up on the time signature of your ship, and dared to hope...